Database Drupal db_select-如何正确地将UNION与LIMIT结合起来？

我正在尝试从按类别划分的数据库中获取内容。我要严格地最多4个“人”类型的条目和3个“组织”类型的其他条目

我试着这样做：

    $query = db_select('node', 'n')
    ->fields('n', array('title','type'))
    ->fields('i', array('field_image_fid'))
    ->fields('f', array('uri'))
    ->condition('n.title', '%'. db_like($keys) . '%', 'LIKE')
    ->condition('type', array('people'))
    ->range(0,4);
    $query->leftJoin('field_data_field_image', 'i', 'i.entity_id = n.nid');
    $query->leftJoin('file_managed', 'f', 'f.fid = i.field_image_fid');

    $query2 = db_select('node', 'n')
    ->fields('n', array('title','type'))
    ->fields('i', array('field_image_fid'))
    ->fields('f', array('uri'))
    ->condition('n.title', '%'. db_like($keys) . '%', 'LIKE')
    ->condition('type', array('organization'))
    ->range(0,4);
    $query2->leftJoin('field_data_field_image', 'i', 'i.entity_id = n.nid');
    $query2->leftJoin('file_managed', 'f', 'f.fid = i.field_image_fid');

    $query->union($query2, 'UNION');
    $result = $query
    ->execute();

问题是，此查询只返回前三次出现的人员或组织的组合。因此，如果查询返回了三个人，我将无法看到任何组织

我也试过这样的方法：

$query = db_query('

        SELECT p.title,p.type 
            FROM node as p
            WHERE p.type = :type 
            LIMIT 4'
        , array(':type' => 'people',':type1' => 'organization'))->fetchAll();

$query2 = db_query('

        SELECT o.title,o.type 
            FROM node as o
            WHERE o.type = :type1 
            LIMIT 4'
        , array(':type' => 'people',':type1' => 'organization'))->fetchAll();


$query->union($query2, 'UNION');

$result = db_query('

        SELECT title,type 
            FROM {node} 
            WHERE type = :type 
            LIMIT 4 
        UNION ALL
        SELECT title,type 
            FROM {node} 
            WHERE type = :type1 
            LIMIT 4'
        , array(':type' => 'people',':type1' => 'organization'))->fetchAll();

或者像这样：

$query = db_query('

        SELECT p.title,p.type 
            FROM node as p
            WHERE p.type = :type 
            LIMIT 4'
        , array(':type' => 'people',':type1' => 'organization'))->fetchAll();

$query2 = db_query('

        SELECT o.title,o.type 
            FROM node as o
            WHERE o.type = :type1 
            LIMIT 4'
        , array(':type' => 'people',':type1' => 'organization'))->fetchAll();


$query->union($query2, 'UNION');

$result = db_query('

        SELECT title,type 
            FROM {node} 
            WHERE type = :type 
            LIMIT 4 
        UNION ALL
        SELECT title,type 
            FROM {node} 
            WHERE type = :type1 
            LIMIT 4'
        , array(':type' => 'people',':type1' => 'organization'))->fetchAll();

但这两种方法只返回4个人，没有组织，我的意思是永远不会

---

如果你能帮忙，谢谢你

查询中的Union语句实际从第一个查询中获取记录，并将第一个查询的结果记录合并到第二个查询结果记录

例如，第一种情况在联合查询中不使用limit，而是给出所有记录

 $query1 = db_select('node', 'n')
   ->fields('n', array('nid','title','type'))
   ->condition('type', array('people'));

 $query2 = db_select('node', 'n')
  ->fields('n', array('nid','title','type'))
  ->condition('type', array('organization'));

 $query = Database::getConnection()
    ->select($query1->union($query2))
    ->fields(NULL, array('nid','title', 'type'))
    ->orderBy('nid');           
 $result = $query->execute()->fetchAll();

从上面的查询中，它会在第二个查询的记录之前追加第一个查询的记录

根据您的示例，如果您希望从人员内容类型获取4条记录，从组织内容类型获取3条记录
使用以下查询来解决您的问题

  $query1 = db_select('node', 'n')
   ->fields('n', array('nid','title','type'))
   ->condition('type', array('people'))
   ->range(0,4);
  $query2 = db_select('node', 'n')
  ->fields('n', array('nid','title','type'))
  ->condition('type', array('organization'));
  ->range(0,7);
 $query = Database::getConnection()
    ->select($query1->union($query2))
    ->fields(NULL, array('nid','title', 'type'))
    ->orderBy('nid');           
 $result = $query->execute()->fetchAll();